Without limiting the scope of the invention, its background is described in connection with ear wax removal.
Cerumen (ear wax) is a slightly yellow waxy substance that is found in the ear canal of humans and other mammals. Ear wax is composed of a variety of waxes secreted by ceruminous glands located in the ear canal; sebum from oil glands, desquamated epithelial cells, along with other materials. Together, these materials combine to form a greasy wax that helps protect the passageway into the ear. Cerumen also acts as a demulcent, forming a protective layer over the skin of the external ear canal. The composition, as well as physical characteristics of ear wax, including quantity, consistency and color of ear wax varies among individuals. These factors, along with genetic factors and regular ear hygiene contribute to accumulation of ear wax and difficulties that can be encountered when trying to remove it.
Accumulation and impaction of ear wax in the external ear canal is a significant problem. Cerumen impaction occurs more frequently in older populations, among people who wear hearing aids and ear plugs and is associated with overuse of cotton buds used to swab the ear canal, as well as in individuals with congenital deformities of the ear canal. Individuals possessing hairy ear canals are also disposed to ear wax build-up. Additionally, ear wax accumulation can also be a problem in infants. Individuals who experience accumulation or impaction of ear wax may suffer ear pain, difficulty in hearing, tinnitus, irritation and itching. It is usually necessary to remove ear wax to alleviate these conditions. Physician office visits are common, necessary and can be costly for the purpose of removing excess or impacted cerumen from patients' ears.
Over-the-counter (OTC) wax softening products often contain carbamide peroxide as an active ingredient (FDA monograph part 344.). Debrox Drops Earwax Removal Aid, available from Smith Kline Beecham of Pittsburgh, Pa. is one such product; another is Murine Ear drops manufactured by Abbott Laboratories, Columbus, Ohio, Flents Earwax Remover is produced by Flents Products Co of Yonkers, N.Y. These monographed products contain 6.5% carbamide peroxide in a glycerin vehicle. To use these products, drops are placed in the affected ear, the individual waits a few minutes and then tilts his/her head to the side to allow drainage of excess liquid. In addition to OTC earwax remedies, a prescription product, Cerumenex Eardrops, is also available. The product contains triethanolamine polypeptide oleate-condensate (10%), as an active ingredient, and is available from the Purdue Frederick Company of Norwalk, Conn. Triethanolamine polypeptide oleate-condensate is a surfactant that helps emulsify ear wax; an application of the product requires about 30 minutes. Cerumenex sometimes results in irritation of the ear canal, a type of localized dermatitis.
In addition to the foregoing, other preparations have been used to soften and help remove ear wax. These agents include sodium bicarbonate, hydrogen peroxide, glycerin and oils, such as olive oil, mineral oil, etc. Most commonly, when one of these remedies is used, irrigation with warm water or saline solution is employed to help remove cerumen.
Hydrogen peroxides can sometimes cause irritation of the ear canal. U.S. patents have covered some of these kinds of products. For instance, U.S. Pat. No. 5,296,472 (Sanchez et al) describes oil-free cyclodextrin compositions that are useful for cerumen removal; U.S. Pat. No. 4,895,875 (Winston) discloses compositions containing stabilized hydrogen peroxide, urea, and glycerin that have utility for the removal of ear wax; and U.S. Pat. No. 5,480,658 (Melman) discloses compositions comprising acetic acid and boric acid in a water base useful for cleaning the external ear canal of pets.
Aqueous solutions of percent sodium bicarbonate (5%) have also been used by physicians to remove accumulated ear wax. Glycerin may also be added because of its abilities to soften cerumen and its demulcent activity. Because products containing sodium bicarbonate are not stable, products of this type must be compounded relatively frequently and to date have not been commercialized.
Several home remedies, OTC products, and a surfactant-containing prescription are available and used for removal of cerumen. Nonetheless, a clear-cut need remains for improved compositions that will remove ear wax from animals and humans in a relatively short period of time and do so safely. Products that have the ability to soften or dissolve impacted ear wax and also quickly, and can be used to help prevent accumulation of ear wax will also be of significant benefit.
Liquid semifluorinated alkanes (SFAs) have been used commercially for medical purposes for about two decades. SFAs are used in the eye to replace vitreous humor, the material located posterior to the crystalline lens; as a tamponade in retinal detachment and as an adjunct to unfolding and holding in place a detached retina (Meinert, H. et al., Europ J Ophthalmol. 10(3), p 583-595. 1993). Such application has shown SFAs to be well-tolerated, even in sensitive and delicate organs such as the inside of the eye.